From the official PR:
NVIDIA Corporation today raised the performance bar in graphics performance by being the first graphics solution with one gigahertz (1GHz) double data rate (DDR) II synchronous RAM. Working closely with Samsung Electronics Corporation, the leading DDR memory manufacturer, NVIDIA and the new NVIDIA® GeForce™ FX graphics processing unit (GPU) uses 1GHz DDR II graphics memory devices---doubling the bandwidth, and providing the industry's fastest frame rates at higher resolutions and higher color depths than ever before. Furthering its track record of graphics technology leadership, the NVIDIA GeForce FX GPU will be the first graphics solution to ship with next generation high-speed DDR II memory.

There are a few previews around the web already: Anandtech, HardOCP, FiringSquad & B3D.